Absorption of hydromagnetic waves in the ionosphere

1970 ◽  
Vol 48 (3) ◽  
pp. 362-366
Author(s):  
M. Abbas
Keyword(s):  
Magnetic Field ◽  
Frequency Range ◽  
Parallel Propagation ◽  
Hydromagnetic Waves ◽  
The Magnetic Field

Absorption of hydromagnetic waves in the ionosphere propagated normal to the magnetic field is calculated at various frequencies and compared with the absorption for parallel propagation. Data corresponding to both daytime and nighttime ionospheres are used. Waves propagated normal to the magnetic field are highly absorbed through the daytime ionosphere at frequencies above a few Hz; the nighttime ionosphere, however, is virtually transparent to waves in the frequency range of 10−3 to 20 Hz. A comparison of the absorption processes for waves propagated parallel and normal to the magnetic field is made.

scholarly journals Practice and perspectives of using ultrasensitive magnetometers in biomedical research.

2021 ◽  
Author(s):  
Yu.V. Maslennikov ◽  
◽  
◽  
Keyword(s):  
Magnetic Field ◽  
Biomedical Research ◽  
Magnetic Measurements ◽  
Signal To Noise Ratio ◽  
Frequency Range ◽  
Optically Pumped ◽  
Technical Solutions ◽  
Further Development ◽  
The Magnetic Field

There are a large number of sensors for measuring the magnetic field of biological objects. They are characterized by the type of the measured physical parameter (magnetic field strength, magnetic flux, etc.), the level of intrinsic sensitivity, and the frequency range of the recorded signals. The long-term practice of studying biomagnetic signals shows that only SQUID-based magnetometers and optically pumped magnetometers have sensitivity levels sufficient for recording biomagnetic signals with the required signal-to-noise ratio. This chapter reflects the main directions of using such magnetometers and methods of magnetic measurements in biomedical research, gives examples of existing technical solutions, and shows possible ways of their further development.

scholarly journals Multi-frequency pulsar studies at high radio frequencies

1996 ◽  
Vol 160 ◽  
pp. 279-282
Author(s):  
Michael Kramer ◽  
Kiriaki M. Xilouris
Keyword(s):  
Magnetic Field ◽  
Flux Density ◽  
Stellar Surface ◽  
Active Part ◽  
Frequency Range ◽  
Density Spectrum ◽  
Density Measurements ◽  
Radio Frequencies ◽  
Dipolar Structure ◽  
The Magnetic Field

AbstractWe report flux density measurements, polarimetric and timing observations of pulsars made at the highest radio frequencies to date, covering the widest frequency range from 1.4 GHz to 86 GHz. We find that the magnetic field maintains its dipolar structure throughout the active part of the magnetosphere, a region located close to the stellar surface and confined to a small slab of a few stellar radii. The change in width and shape of pulse profiles saturates at mm-wavelengths while the depolarization accelerates, leading to almost completely depolarized emission. Two pulsars seem to exhibit a turn-up in their flux density spectrum at mm-wavelengths.

Optical waveguide switch through magnetic reflectance wall

2016 ◽  
Vol 30 (19) ◽  
pp. 1650119
Author(s):  
Yuntuan Fang ◽  
Zhiyao Ni ◽  
Lixia Yang
Keyword(s):  
Magnetic Field ◽  
Optical Waveguide ◽  
Mode Analysis ◽  
Photonic Crystal Waveguide ◽  
Frequency Range ◽  
Yttrium Iron ◽  
Iron Garnet ◽  
Rod Array ◽  
Two Sides ◽  
The Magnetic Field

We propose a new design to achieve optical waveguide switch. We construct a photonic crystal waveguide with one yttrium iron garnet (YIG) rod array on the two sides of the waveguide. Through the mode analysis, we find in special frequency range a few YIG rods under magnetic field can form the magnetic reflectance wall that blocks the light flow. Removing the magnetic field will delete the reflection wall and let the blocked light to be switched on.

scholarly journals Совместное влияние магнитного поля и спин-поляризованного тока на связанную динамику магнитных вихрей в спин-трансферном наноосцилляторе

2021 ◽  
Vol 47 (17) ◽  
pp. 26
Author(s):  
Е.Г. Екомасов ◽  
С.В. Степанов ◽  
В.Н. Назаров ◽  
К.А. Звездин ◽  
Н.Г. Пугач ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Joint Effect ◽  
Spin Transfer ◽  
Frequency Range ◽  
Magnetic Vortices ◽  
Coupled Oscillations ◽  
Operating Frequency Range ◽  
Spin Polarized ◽  
Micromagnetic Modeling ◽  
The Magnetic Field

The joint effect of the spin polarized current and an external magnetic field on the dynamics of magnetization in vortex spin-transfer nano-oscillators with a diameter of 400 nm is investigated. For the numerical calculation of the coupled dynamics of magnetic vortices, the SpinPM software package for micromagnetic modeling was used. The dependence of the frequency of stationary coupled oscillations of vortices on the magnitude of the magnetic field, which determines the operating frequency range of a tunable vortex spin-transfer nano-oscillator.

Localization of Dead Open in a Solder Bump by Space Domain Reflectometry

2012 ◽  
Author(s):  
David P. Vallett ◽  
Daniel A. Bader ◽  
Vladimir V. Talanov ◽  
Jan Gaudestad ◽  
Nicolas Gagliolo ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Failure Analysis ◽  
Quantum Interference ◽  
Flip Chip ◽  
Solder Bump ◽  
Frequency Range ◽  
Superconducting Quantum Interference Device ◽  
Space Domain ◽  
Non Destructive ◽  
The Magnetic Field

Abstract Space Domain Reflectometry (SDR) is a newly developed non-destructive failure analysis (FA) technique for localizing open defects in both packages and dies through mapping in space domain the magnetic field produced by a radio frequency (RF) current induced in the sample, herein the name Space Domain Reflectometry. The technique employs a scanning superconducting quantum interference device (SQUID) RF microscope operating over a frequency range from 60 to 200 MHz. In this paper we demonstrate that SDR is capable of locating defective micro bumps in a flip-chip device.

Effect of Magnetic Field on the Magnetic Structure of Nanocrystalline Electroplated NiFe Layers

2005 ◽  
Vol 23 ◽  
pp. 167-170
Author(s):  
Xiao Ping Li ◽  
Z.J. Zhao ◽  
T.B. Oh ◽  
H.L. Seet
Keyword(s):  
Magnetic Field ◽  
Magnetic Structure ◽  
High Frequency ◽  
Longitudinal Magnetic Field ◽  
High Sensitivity ◽  
Frequency Range ◽  
Gmi Effect ◽  
Double Peaks ◽  
Field Sensor ◽  
The Magnetic Field

In order to develop high sensitivity micro sensors for bio-magnetic field using NiFe electroplated composite sensing elements, it is important to study how different plating processes can affect the magnetic properties in terms of the chemical composition and magnetic structure of the plated layer. In this study, to study the effect of the magnetic field on the magnetic structure of the electroplated NiFe layers, magnetic controlled plating in which a longitudinal magnetic field ranging from 0 to 400 Oe is applied during nanocrystalline electroplating of permalloy Ni80Fe20 layer of 2 µm thick onto a 20 µm diameter Cu wire. The magnetic structure of the plated layers is studied by investigating the Giant magneto-impedance (GMI) effect of the plated layer. GMI has been measured from a frequency range of 100 kHz to 50 MHz. It is observed that under conventional electroplating without an external magnetic controlling field, the anisotropy of the plated layer is generally circumferential as indicted by the double peaks of the MI curves in testing at high frequency. When a longitudinal magnetic field is applied during electroplating, the plated layer shows single peak MI curves, suggesting that the anisotropy is changed from circumferential to longitudinal. The results also show that the sensitivity and resolution of a magnetic field sensor is improved greatly by changing the anisotropy of the plated layer from circumferential to longitudinal.

Resonantly unstable off-angle hydromagnetic waves

1967 ◽  
Vol 1 (1) ◽  
pp. 81-104 ◽  
Author(s):  
C. F. Kennel ◽  
H. V. Wong
Keyword(s):  
Magnetic Field ◽  
High Energy ◽  
Electrostatic Waves ◽  
High Energy Tail ◽  
Electrons And Ions ◽  
Ion Cyclotron ◽  
Cold Component ◽  
Hydromagnetic Waves ◽  
The Magnetic Field ◽  
Uniform Plasma

We consider semi-quantitatively the cyclotron resonance instability of ion cyclotron and magnetosonic waves propagating at an angle to the magnetic field in an infinite uniform plasma. The velocity distributions of electrons and ions consist of a dense cold component and a diffuse high-energy tail. If the high-energy protons are sufficiently intense and their pitch angle distributions sufficiently anisotropic, instability occurs for those waves propagating parallel to the magnetic field. If the spectrum of resonant protons is sufficiently hard, a reasonably large cone of propagating angles about the magnetic field can be unstable. Observed fluxes of trapped protons in the magnetosphere should destabilise the ion cyclotron wave at a lower intensity threshold than for at least one class of electrostatic waves.

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